This FIRST AMENDMENT TO LEASE, dated January 13, 1997 (this
"Amendment"), between RCPI Trust, having an office c/o Tishman Speyer
Properties, L.P., 45 Rockefeller Plaza, New York, New York 10111 ("Landlord"),
and ACTV, Inc., having an office at 1270 Avenue of the Americas, New York, New
York 10020 ("Tenant").

                              W I T N E S S E T H:

                  WHEREAS, Landlord (as successor to Rockefeller Center
Properties) and Tenant executed and exchanged that certain Lease, dated January
23, 1996 (the "Original Lease"), covering a portion of the 24th Floor (the
"Premises") in the building located at 1270 Avenue of the Americas, New York,
New York (the "Building"), all as more particularly described in the Original
Lease; and

                  WHEREAS, Landlord and Tenant desire to modify the Original
Lease (I) to lease to Tenant certain additional space in the Building and (ii)
to otherwise modify the terms and conditions of the Original Lease as
hereinafter provided (the Original Lease, as modified by this Amendment, being
hereinafter referred to as the "Lease").

                  NOW, THEREFORE, in consideration of the mutual covenants
herein contained, and other good and valuable consideration, the receipt and
sufficiency of which is hereby acknowledged, Landlord and Tenant agree that the
Original Lease shall be modified as follows:

                  1. Capitalized Terms; Recitals; Definitions. All defined terms
used herein and not otherwise defined in this Amendment shall have the meanings
ascribed to them in the Lease. The recital clauses set forth above are
incorporated herein by reference.

                  2.  Demise of Additional Premises, Term and Rent.

                  (a) Landlord hereby leases to Tenant, and Tenant hereby leases
from Landlord, a portion of the 24th Floor of the Building substantially as
shown on Exhibit A annexed hereto and made a part hereof and designated as space
`C' (the Additional Premises") for a term to commence on the date upon which
landlord offers Tenant possession of the Premises with the Landlord's Work (as
defined in Paragraph 6 of this Agreement) substantially completed (subject to
Article Two of the Premises Commencement Date") and to end on January 31, 2001
(the Expiration Date") subject to the terms and conditions of the Lease, except
as otherwise expressly provided herein.

                  (b) The fixed rent payable under the Original Lease shall be
increased by $57,552.00 per annum during the period commending on the fixed rent
payable under the Original Lease shall be increased by $57,552.00 per annum
during the period commending on the Additional Premises Commencement Date and
ending on the day preceding the third anniversary of the Additional Premises
Commencement Date; and $61,040.00 per annum thereafter. Tenant hereby covenants
and agrees to pay said fixed rent as so increased and the additional rent
payable under the Original Lease, at the times and in the manner specified in
the Original Lease for the payment of fixed rent and additional rent.
Notwithstanding the foregoing, provided Tenant is not in default beyond any
applicable notice and grace period, the fixed rent payable with respect to the
Additional


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Premises shall be abated at the rate of $4,796.00 per month for the period
commencing on the Additional Premises Commencement Date and ending on the two
month anniversary of Additional Premises Commencement Date (the "Rent
Commencement Date"), which abatement shall be deemed an abatement of fixed rent
under Article One.

                  (c) Effective as of the Additional Premises Commencement Date,
the term "Premises" shall be deemed to include the Additional Premises except
that, (I) in applying the provisions of Article One of the Original Lease to the
Additional Premises, (a) "Premises" shall mean the Additional Premises only; and
(b) the "term commencement date" shall mean the Additional Premises Commencement
Date; and (ii) Articles Thirty, Thirty-one and Thirty-three of the Original
Lease shall not apply to the Additional Premises. Nothing contained in the
Amendment shall give to Tenant any option for the renewal or extension of the
term hereby granted with respect to the Additional Premises.

                  3.  Article Two of the Original Lease shall be amended with
respect to the  Additional Premises only as follows:

                     "Landlord shall not be liable for failure to deliver
                  possession of the Additional Premises on any specified date.
                  There shall be no postponement of the Additional Premises
                  Commencement Date for any Tenant Delay or Delay by Landlord in
                  the performance of minor details of construction or mechanical
                  adjustments which the Landlord is obligated to perform. The
                  foregoing shall constitute `an express provision to the
                  contrary' as such phrase is used in Section 223-a of the Real
                  Property Law of the State of New York and shall constitute a
                  waiver of Tenant's rights pursuant to such Section 223-a and
                  any other law of like import now or hereafter in force."

                  4. Broadcast  Restrictions. Article Three of the Original
Lease is amended by adding the following paragraph as Section 3.6.:

                     "Landlord has entered into a Declaration of Covenants and
                  Restrictions with National Broadcasting Company, Inc., dated
                  as of July 17, 1996, a memorandum of which has been recorded
                  in the Office of the Register of the City of New York, New
                  York County (the "Declaration"), pursuant to which Landlord
                  agreed to include, in all leases, licenses and occupancy
                  agreements for space in the Center entered into from and after
                  the date of the Declaration, certain restrictions on the
                  ability of the tenants, licensees and other occupants under
                  such agreements to conduct, allow or permit certain broadcast
                  and related activities in the Center (the Restrictions"). A
                  copy of the Restrictions is attached to this Lease as Exhibit
                  B. Tenant agrees that it shall not take or fail to take, or
                  permit, cause or allow to be taken, any action, and shall not
                  enter into any arrangement, which would violate or cause a
                  violation of the Restrictions."

                  5. Effective on and after the Additional Premises Commencement
Date, Section 7.2.3. of the Original Lease shall be amended with respect to the
Additional Premises only, by deleting it in its entirety and substituting
therefor the following:

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                     "The term `Applicable Rental Rate' as used in this Article
                  shall mean $33.00 per annum during the period commencing on
                  the Additional Premises Commencement Date and ending on the
                  day preceding the third anniversary of the Additional Premises
                  Commencement Date; and $35.00 per annum thereafter."

                  6. Effective on and after the Additional Premises Commencement
Date, Section 24.3(I) of the Original Lease shall be amended by deleting the
date "December 1, 1996" where it appears therein and substituting therefor the
date "December 31, 1996".

                  7. Effective on and after the Additional Premises Commencement
Date, Article Twenty-six of the Original Lease shall be restated in its entirety
to read as follows:

                     26.1. Tenant shall deposit the amount of $120,181.25 (the
                  "Security Deposit") with Landlord upon the execution of this
                  Lease in cash as security for the faithful performance and
                  observance by Tenant of the terms, covenants and conditions of
                  this Lease, including the surrender of possession of the
                  Premises to Landlord as herein provided. Landlord confirms
                  that Tenant has previously deposited with Landlord the amount
                  of $52,181.25.

                     26.2. In lieu of a cash deposit, Tenant may deliver the
                  Security Deposit to Landlord in the form of a clean,
                  irrevocable, non-documentary and unconditional Letter of
                  Credit issued by and drawable upon any commercial bank, trust
                  company, national banking association or savings and loan
                  association with offices for banking purposes in the City of
                  New York the "Issuing Bank"), which has outstanding unsecured,
                  uninsured and unguaranteed indebtedness, or shall have issued
                  a letter of credit or other credit facility that constitutes
                  the primary security for any outstanding indebtedness (which
                  is otherwise uninsured and unguaranteed), that is then rated,
                  without regard to qualification of such rating by symbols such
                  as "+" or "-" or numerical notation, "Aa" or better by Moody's
                  Investors Service and "AA" or better by Standard & Poor's
                  Ratings Service, and has combined capital, surplus and
                  undivided profits of not less than $500,000,000. Such Letter
                  of Credit shall (a) name Landlord as beneficiary, (b) be in
                  the amount of the Security Deposit, (c) have a term of not
                  less than one year, (d) permit multiple drawings, (e) be fully
                  transferable by Landlord without the payment of any fees or
                  charges, and (f) otherwise be in form and content satisfactory
                  to Landlord; provided, however, that Landlord shall in no
                  event be obligated to accept a Letter of Credit for any amount
                  less than $25,000. If upon any transfer of the Letter of
                  Credit, any fees or charges shall be so imposed, then such
                  fees or charges shall be payable solely by Tenant and the
                  Letter of Credit shall so specify. The Letter of Credit shall
                  provide that it shall be deemed automatically renewed, without
                  amendment, for consecutive period of one year each thereafter
                  during the Term, unless the issuing Bank sends a

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                  notice (the "Non-Renewal Notice") to Landlord by certified
                  mail, return receipt requested, not less than 45 days next
                  preceding the then expiration date of the Letter of Credit,
                  stating that the Issuing Bank has elected not to renew the
                  Letter of Credit. Landlord shall have the right, upon
                  receipt of a Non-Renewal Notice, to draw the full amount of
                  the Letter of Credit, by sight draft on the Issuing Bank,
                  and shall thereafter hold or apply the cash proceeds of the
                  Letter of Credit pursuant to the terms of this Article
                  Twenty-six. The Issuing Bank shall agree with all drawers,
                  endorsers and bona fide holders that drafts drawn under and
                  in compliance with the terms of the Letter of Credit will be
                  duly honored upon presentation to the Issuing Bank at an
                  office location in Manhattan. The Letter of Credit shall be
                  subject in all respects to the Uniform Customs and Practice
                  for Documentary Credits (1993 revision), International
                  Chamber of Commerce Publication No. 500.

                     26.3. If Tenant defaults in the payment or performance of
                  any the terms, covenants or conditions of this Lease,
                  including the payment of Rent, Landlord may apply or retain
                  the whole or any part of the cash Security Deposit or may
                  apply or retain the whole or any part of the cash Security
                  Deposit or may notify the Issuing Bank and thereupon receive
                  all or a portion of the Security Deposit represented by the
                  Letter of Credit, and use, apply, or retain the whole or any
                  part of such proceeds, as the case may be, to the extent
                  required for the payment of any Rent or any other sum as to
                  which Tenant is in default, including (a) any sum which
                  Landlord may expend or may be required to expend by reason of
                  Tenant's default, and (b) any damages to which Landlord is
                  entitled pursuant to this Lease or applicable Requirements,
                  whether such damages accrues before or after summary
                  proceedings or other reentry by Landlord. If Landlord applies
                  or retains any part of the Security Deposit, Tenant, upon
                  demand, shall deposit with Landlord the amount so applied or
                  retained so that Landlord shall have the full Security Deposit
                  on hand at all times during the Term. If Tenant shall fully
                  and faithfully comply with all of the terms, covenants and
                  conditions of this Lease, the Security Deposit shall be
                  returned to Tenant after the expiration or earlier termination
                  of this Lease and after delivery of possession of the Premises
                  to Landlord in the manner required by this Lease. Tenant
                  expressly agrees that Tenant shall have no right to apply any
                  portion of the Security Deposit against any of Tenant's
                  obligations to pay Rent hereunder, and if Tenant shall seek to
                  so apply the Security Deposit, Tenant shall pay liquidated
                  damages to Landlord in a sum equal to two times the amount of
                  any such unpaid Rent.

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                     26.4. Upon a sale of the Building or the Land or a leasing
                  of the Building, or any financing of Landlord's interest
                  therein, Landlord shall have the right to transfer the cash
                  Security Deposit or the Letter of Credit, as applicable, to
                  the vendee, lessee or lender. With respect to the Letter of
                  Credit, within five days after notice from Landlord of such
                  sale, leasing or financing, Tenant, at its sole cost, shall
                  arrange for the transfer of the Letter of Credit to the new
                  landlord or lender, as designated by Landlord in the foregoing
                  notice, or to have the Letter of Credit reissued in the name
                  of the new landlord or lender. Tenant shall look solely to the
                  new landlord or lender for the return of such cash Security
                  Deposit or Letter of Credit, and the provisions of the Section
                  26.4. shall apply to every transfer or assignment made of the
                  Security Deposit to a new landlord. Tenant will not assign or
                  encumber, or attempt to assign or encumber, the cash Security
                  Deposit or Letter of Credit, and neither Landlord not its
                  successors or assigns shall be bound by any such actual or
                  attempted assignment or encumbrance.

                  26.5 If (i) no default with respect to Tenant's obligation to
                  pay Rent on a timely basis under the Lease has occurred during
                  the term and (ii) Tenant is not then in default in the due
                  keeping, observance or performance of any term or condition of
                  the Lease, then on and after the date which is the condition
                  of the Lease, then on and after the date which is the (a)
                  twelve month anniversary of the Rent Commencement Date, the
                  Security Deposit shall be $106,181.25; (b) eighteen month
                  anniversary of the Rent Commencement Date, the Security
                  Deposit shall be $92,181.25; and (c) thirty-six month
                  anniversary of the Rent Commencement Date, the Security
                  Deposit shall be $62,181.25. In event of any reduction of the
                  Security Deposit as hereinabove provided, Landlord shall
                  return to Tenant any amount held by Landlord in excess of the
                  Security Deposit."

                  8.  Article Thirty-four of the Original Lease is hereby
deleted in its entirety.

                  9. Landlord's Work. Prior to the Additional Premises
Commencement Date, Landlord, at its sole cost and expense, shall construct a
doorway at a location to be mutually agreed upon by Landlord and Tenant (which
shall be of material, manufacture, design, quality, finish and color of the
standard adopted by Landlord for the Building) with respect to the Additional
Premises (the "Landlord's Work"). Landlord shall provide Tenant with five (5)
days prior Notice of the date upon which Landlord's Work shall be substantially
completed.

                  10. Tenant Allowance. Landlord agrees that (I) if Tenant is
not then in default under the Lease, (ii) upon receipt by it of evidence
satisfactory to it of the completion of painting and carpeting the Additional
Premises in a manner reasonably to Landlord, and (iii) upon the furnishing by
Tenant to Landlord of the evidence of the payment therefor by Tenant, Landlord

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shall reimburse to Tenant the lesser of (a) the payment of the actual cost of
such painting and carpeting, or (b) $5,467.00.

                  11.  Brokerage

                  (a) Each of Landlord and Tenant represents and warrants to the
other that it has not dealt with any broker in connection with this Amendment
other than Tishman Speyer Properties, L.P. ("Broker") and that, to the best of
its knowledge, no other broker negotiated this Amendment or is entitled to any
fee or commission in connection herewith. The execution and delivery of this
Amendment by each party shall be conclusive evidence that each party has relied
upon the foregoing representations and warranties.

                  (b) Each of Landlord and Tenant shall indemnify, defend,
protect and hold the other party harmless from and against any and all losses,
liabilities, damages, claims, judgments, fines, suits, demands, costs, interest
and expenses of any kind or nature (including reasonable attorney's fees and
disbursements) incurred in connection with any claim, proceeding or judgment and
the defense thereof which the indemnified party may incur by reason of any claim
of or liability to any broker, finder or like agent (other than Broker) arising
out of any dealings claimed to have occurred between the indemnifying party and
the claimant in connection with this Amendment, or the above representation
being false. The provisions of this Paragraph 11 shall survive the expiration or
earlier termination of the term of this Amendment.

                  12. No Modification. Except  as  set  forth  herein, nothing
contained in this Amendment shall be deemed to amend or modify in any respect
the terms, provisions, or conditions of the Lease and such terms, provisions,
and conditions shall remain in full force and effect as modified hereby.

                  13. Representations. Landlord and Tenant each represents and
warrants to the other that as of the date hereof, (I) the Lease is in full force
and effect and (ii) no written notices default have been delivered by Landlord
or Tenant to the other party and remain outstanding.

                  14.  Miscellaneous.

                  (a) This Amendment contains the entire understanding of the
parties with respect to the subject matter hereof.

                  (b) This Amendment shall be governed by the laws of the State
of New York without giving effect to conflict of laws principles thereof.

                  (c) This Amendment shall be binding upon and inure to the
benefit of Landlord and Tenant and their successors and permitted assigns.

                  (d) The captions, headings, and titles in this Amendment are
solely for convenience of reference and shall not affect its interpretation.

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IN WITNESS WHEREOF, Landlord and Tenant have executed this Amendment as of the
day and year first above written.

                                  RCPI TRUST
                                  By Tishman Speyer Properties, L.P., its Agent


                                  By______________________________________
                                              Philip M. Waterman III


                                  ACTV, INC.


                                  By______________________________________
                                                Vice President